“We think, among living biologists, anyway, our group are probably the only group that has seen living specimens,” said Distel.

He added: “To me it was almost like finding a dinosaur – something that was pretty much only known by fossils.”

Distel’s team stumbled across the ship worm’s’ whereabouts thanks to a Philippine television news report on YouTube. The location remains a secret to prevent the site being disturbed by shell collectors.

With the Linnaean classification Kuphus polythalamia, the creature lives in the mud inside a long tube made of calcium carbonate secreted by the animal. The tube forms a casing for the beast, including its head. “If they want to grow, they have to open that end of that tube, so somehow dissolve or reabsorb that cap on the bottom, grow, extend the tube down further into the mud, and then they seal it off again,” said Distel.

The end of the tube, adds Distel, is Y-shaped and surrounds two siphons – water is drawn in through one, pushed through the creature’s gills, then expelled through the other.

Despite being known as a shipworm – a nod to its relatives’ diet of submerged wood – the animal is actually a type of clam. It has a modified version of two clam shells at its head, while the body stretches out behind. “Its body has been stretched out through evolution so that it no longer fits between the two shells,” said Distel.

Distel explained that the discovery “sheds light on the evolution of symbiotic relationships between sulphur-oxidising organisms and other creatures, and backs up the possibility that sunken wood might have played a role in how such species ended up in locations such as deep sea hydrothermal vents.”